1 Field of the Invention
The present invention relates to a mobile telephone comprising a housing containing an electrical circuit and carrying a cover fastened to this housing in an articulated i.e., jointed manner and further comprising a microphone.
2 Description of Prior Development
French Patent Application No. 97 00 891 of Jan. 28, 1997 in Applicant""s name describes a mobile telephone of the above type, in which rotary contacts are incorporated in one of the two joints connecting the cover to the housing, in order to make electrical connections between the electrical circuit of the housing and the electrical circuit of the microphone.
The purpose of the present invention is to make improvements to the above described mobile telephone, the object being to increase the reliability of the electrical connection made by the rotary contacts and also to simplify the assembly of the housing and of the cover.
According to the invention, the mobile telephone is characterized in that one of the joints articulating the housing on the cover comprises three contacts integral with the housing, i.e. two lateral contacts and a central contact. Each of the contacts comprise a contact arm. The central contact bears permanently on a conductive element, while the ends of the two lateral contact arms bear elastically on two conductive plates separated by an insulating material and incorporated in part of the joint of the cover. This is in such a way whereby when the cover is rotated the ends of the two lateral contact arms ensure that the electrical connection between the electrical circuit of the housing and the electrical circuit of the microphone is switched.
During the rotation of the cover, the three contacts brush against the conductive plates. This brushing produces a self-cleaning effect, making it possible to ensure that the electrical connection has a high degree of reliability.
Preferably, the two arms of the lateral contacts and the two contact plates on which they bear are symmetrical with respect to the axis of the joint.
The position of the conductive plates with respect to the contact arms is such that, when the cover is folded down onto the housing, the end of one of the lateral contact arms bears on the insulating material contained between the two conductive plates.
Thus, when the cover is closed, no electrical current circulates between the electrical circuit of the housing and the electrical circuit of the microphone carried by the cover.
This avoids premature wear of the battery supplying the appliance when the latter is not being used.
Moreover, when an incoming call arrives, the detection of the opening of the cover as a result of the closing of the electrical circuit of the microphone thus makes it possible to xe2x80x9cpick upxe2x80x9d the receiver, without a button having to be manipulated.
According to a preferred version of the invention, each contact consists of a piece cut out from a metal sheet and comprises two arms, one forming the contact arm and the second being folded round the base of a first block of insulating material, incorporated in the joint of the housing, and being in contact at its end with the electrical circuit of the housing.
It should be noted that two types of contacts may be used here, namely contacts cut out on edge and bowed flat contacts having a spoon-shaped end.
Such an embodiment makes it possible to reduce the number of components, make mounting easier and increase reliability.
For the same reasons, preferably, the conductive plates each consist of a piece which is cut out from a metal sheet and bent and which is fastened to a second block of insulating material incorporated in the joint of the cover.
According to an advantageous version of the invention, the joint of the housing comprises a frustoconical surface which is centred on the axis of the joint and into which engages a complimentary frustoconical surface of the joint of the cover.
This engagement allows perfect centring of the two parts of the joint and, in particular, of the contact arms with respect to the conductive plates.
Preferably, the other joint articulating the housing on the cover comprises a spring bringing the two abovementioned complementary frustoconical surfaces to bear one on the other, some play being provided between the two parts of the said other joint, in order to make it possible to remove the cover by the compression of the spring and the disengagement of the two complementary frustoconical surfaces.
It is thus easy to demount the cover in order to replace it with a new cover.